1.Field of the Invention
The invention relates to a method for the surveillance of a brake device in relation to overload, where the brake device includes a wear readjustment device, is actuatable by pressure, and reaches its load limit in a brake actuation after warming of a selected device component to a permissible temperature, where the thus selected device component follows a pressure-dependent characterizing curve of a value representing the deformation.
2. Brief description of the Background of the Invention Including Prior Art
Such a method is known from the International Patent Application WO-84/00406. This method provides for the surveillance of a brake device of the above-indicated kind relative to overload by measuring the temperature of the selected device component and by furnishing a warning signal if this temperature reaches the maximum permissible value. The method employs temperature sensors for measuring the temperature at or in the neighborhood of the selected device component. The device component can be a brake drum or a brake disk.
The inertia of the temperature surveillance is a disadvantage in the context of this method. The selected device component can already have surpassed the permissible temperature, the brake device can thus already be overloaded before a warning signal is furnished in view of the mentioned inertia.
The German printed Patent Publication DE-OS 2,144,466 to H. Negendank et al. teaches a display apparatus for indicating the state of a brake friction lining of a vehicle. A temperature-sensitive element 40 forms part of an electric circuit 52, 28. This electric circuit can be connected to a display apparatus 50, 56 located remotely from the brake. The element 40 induces the display apparatus for providing a signal in cases where the temperature of the brake lining 14 reaches a predetermined value. While this reference employs a temperature-sensitive element, it appears, however, that a reliable overall determination of a possibly existing temperature overloading of a device, having substantial spatial extension, is not ensured with the reference device.
The German Printed Publication Document DE-AS 1,260,313 to Walter Schwengler teaches a measurement device for measuring the radius of curvature of hot water boiler pumps. It is an object of the reference to determine the curvature state of circular pumps transporting hot media. No suggestion is made in the reference in connection with a safety system for vehicular brake systems. The German Printed Patent Document laid open DE-OS 2,106,411 to Andreas Pitter teaches a pulse generator for a load torque limiting device of a crane, hoist or the like. It appears that this reference is not concerned with temperature induced changes of brake systems.
The Japanese document 62-233715 (A) to Yoichi Nagayama teaches an inclination detecting device for a wheel hub. While the reference is concerned with the wheel of a motor vehicle, it does not address the brake system.